Extraction of finite-energy contributions to the Sivers asymmetry from the analysis of exclusive proton–proton scattering

Abstract

I study the effect of scalar and spin-orbit rescattering terms, in the production of a nonzero Sivers-like asymmetry in proton-proton collisions (inclusive production and Drell-Yan) at moderate center of mass energies √ s < 15 GeV and transverse momentum up to 3 GeV/c. An ultrarelativistic generalization of the Glauber formalism is here used to (i) fit the scalar and spin-orbit interaction terms on proton-proton elastic scattering data, including analyzing power, (ii) transfer such information to inclusive proton-proton scattering. It is shown that the phenomenological interactions responsible for the nonzero analyzing power in protonproton elastic scattering produce a relevant nonzero analyzing power in inclusive processes associated with proton-proton collisions. This could represent a relevant (possibly higher-twist) contribution to the Sivers asymmetry.

Azimuthal asymmetries in exclusive four-particle “Drell-Yan” events

“…What is done here is the probabilistic version of the quantum method used in [40], where one rewrites at parton level the hadron-hadron spin-orbit interactions. The method has some overlap with the 1-gluon exchange used in perturbative models [30,33,34,35,36].…”